EP0411848B1

EP0411848B1 - An on-line moisture control method for powdered or granular materials and a system to execute the method

Info

Publication number: EP0411848B1
Application number: EP90308309A
Authority: EP
Inventors: Room 706 Kureru Kibougaoka 103-1 Hiroshi Ogiri; Murata Kazue; Tanaka Sadaaki
Original assignee: Matsui Mfg Co Ltd
Current assignee: Matsui Mfg Co Ltd
Priority date: 1989-08-01
Filing date: 1990-07-30
Publication date: 1996-02-28
Anticipated expiration: 2010-07-30
Also published as: US5146692A; EP0411848A2; DE69025509T2; ATE134777T1; JPH0363558A; CA2022386A1; JP2863860B2; US5274931A; DE69025509D1; EP0411848A3

Abstract

An on-line moisture control method for powdered or granular materials and a related system to execute the method. A fixed amount of materials are sampled by a material sampling means (8A), transported into a heat treatment chamber (3) having an airtight heating part (4), heated in the chamber (3) while an inert gas is supplied therein and measured the weight by a weight measuring unit (2). The moisture generated by heating the materials is sent to a moisture measuring unit (1) together with the inert gas. An operation unit (10) receives the weight value measured by the weight measuring unit (2) and the titrated value measured by the moisture measuring unit (1), and calculates the moisture content of the materials and displays the value.

Description

1. Field of the Invention

The present invention relates to an on-line moisture control method wherein powdered or granular materials including inorganic materials such as resin and ceramic are automatically sampled and quickly measured the moisture content thereof and to an on-line moisture control system to execute the method.

2. Prior Art

Generally, keeping constant the moisture content of resin materials has been taken a most important problem to maintain good quality of resin products because inappropriate moisture content of resin materials to be supplied into a molding machine causes defects in the products such as silver line or void. Therefore, resin materials are usually dried by the use of a hopper dryer prior to being supplied into the molding machine, see e.g. JP-A- 1216226.
However, resin materials before fed into the hopper dryer are apt to absorb moisture in the air while stored in an intermediate stage silo or a tank for a fixed period of time after a kraft bag or a flexible container which is used to carry resin materials is opened. Accordingly a fixed heating temperature and a fixed heating time are settled for the hopper dryer based on an estimated moisture content of resin materials. But such a conventional method for drying resin materials by the use of hopper dryer leaves further room for improvement in saving labor.
On the other hand, a titration analysis using a Karl Fischer reagent has been conventionally known as a method for analyzing and measuring the moisture content of resin materials. In these days a moisture measuring unit has been developed in which a titration analysis by a Karl Fischer reagent is executed by means of a coulometric method, a volumetric method and an absorptive photometric method, whereby a high accuracy can be obtained.
Figs. 8 and 9 show the basic construction of coulometric moisture measuring unit.
This unit is constructed such that a moisture measuring analyzer 61 which executes a coulometric titration by means of Karl Fischer reagent is connected to a heating chamber 63 to heat samples such as powdered or granular materials. In the chamber 63 connected with the analyzer 61 through a conduit 62, powdered or granular materials 66 put on a boat 65 are transferred and contained by an automatic sample loading unit 67. The moisture produced by heating the materials 66 in the chamber 63 is introduced into the analyzer 61 together with a nitrogen gas fed into the chamber 63, the moisture being titrated and analyzed by a Karl Fischer reagent by the use of coulometric titration. Then the result of the analysis is shown on a display 70.
However, such a moisture analyzer 61 has troublesome problems because following procedures must be repeated for each sampled materials.
In order to feed sampled materials 66 into the heating chamber 63, the boat 65 inserted by opening an insert port 64a of insertion pipe 64 extended from the heating chamber 63 by reducing the caliber is pushed into a sample feeding portion 64b by means of a rod 65a, the materials 66 sampled by a sampling unit (not illustrated) being loaded on the boat 65 thus contained in the pipe 64 after a cap 64c of the feeding portion 64b is removed.
In this case, a feeding machine (not illustrated) which contains sampled materials 66 is mated with the cap 64c so that the opening of the feeding machine fits the opening of cap 64c. After a purge valve 69 is opened to atmosphere, a dried pressurized nitrogen gas supplied through a feed pipe 68b and a drying chamber 68a from a gas cylinder 68 is replaced and discharged in order to prevent the entering of outer air into the heating chamber 63.
Further, after the completion of heat treatment, the materials 66 loaded on the boat 65 are transferred by the automatic loading unit 67 into the insert port 64a of insertion pipe 64 to be discharged.
According to the above-mentioned troublesome problems, as a rule, such a moisture measuring analyzer has been used for quality inspection at a laboratory by a professional inspector. It is hardly possible to sample powdered or granular materials one after another at a molding site and measure the moisture content thereof.

THE INVENTION

An object of the present invention is to provide an on-line moisture control method wherein a fixed amount of powdered or granular materials is automatically sampled and fed into a heat treatment chamber for measuring the moisture content and to provide an on-line moisture control system using the method.
An on-line moisture control method according to the present invention is characterized in that the materials are repetitively sampled by the following steps:

feeding into a gastight heat treatment chamber having a heating means a fixed volumetric amount of the sampled materials delivered from a storage hopper via a measuring means;
heating the materials in said heat treatment chamber while supplying the chamber with a pressurized and dried inert gas;
titrating and analyzing moisture generated by heating the materials in the chamber by supplying the moisture, together with inert gas, to a moisture measuring unit;
discharging the heated materials from the chamber into a receiver of a weight measuring unit provided under said heat treatment chamber and measuring the weight of the discharged materials; and
automatically determining the moisture content of the sampled materials by supplying the moisture content value detected in said moisture measuring unit and the weight measured in said weight measuring unit to a calculating unit.

Such an on-line method is roughly divided into two possible methods; the materials are transported by the use of a mechanical material transporting means, the materials are transported by a transport gas such as an air or an inert gas.
This invention uses a moisture measuring unit which executes a coulometric titration, a volumetric titration or a simple absorptive photometric titration which has been disclosed in Japanese Patent Application 63- 039291, a Karl Fischer reagent being used for all those methods.
To execute the method according to the present invention, an on-line moisture control system is provided, comprising a materials sampling means provided with a hopper having a valve for measuring a fixed volumetric amount of the powdered or granular materials; a gastight heat treatment chamber incorporating a heating means and having a capacity sufficient to contain the fixed amount of sampled materials, said heat treatment chamber being provided under said materials sampling means; a transport pipe provided between said sampling means and said heat treatment chamber, said transport pipe having a control valve to control supply of materials from said sampling means and having a gas vent valve for opening to atmosphere; a moisture measuring unit connecting to an upper part of said heat treatment chamber via a branch pipe having a control valve; a control damper provided under said heat treatment chamber for discharging the materials from in said heat treatment chamber; an inert gas feeding means having a feed port at a lower part of said heat treatment chamber and having a feed pipe incorporating a control valve for controlling introduction of pressurized and dried inert gas into said heat treatment chamber; a weight measuring unit provided under said control damper for weighing the heated materials when discharged from the chamber; and a calculating unit which receives the weight value of sampled materials from said weight measuring unit and the moisture content value of said materials from said moisture measuring unit, said calculation unit calculating the moisture content of the fixed amount of the sampled materials and displaying the calculated moisture content value.
The system may include a material measuring chamber having a weight detection sensor above the heat treatment chamber instead of providing the weighing sensor below the chamber. Further, an on-line moisture control system wherein a fixed amount of materials is transferred by a pneumatic transporting means into a material measuring chamber by the use of material suction unit having a nozzle constructed such that an injection port of pressurized gas is disposed at the initial end side of a material suction port formed at the lateral leading portion of said transport pipe so as to be opposite to the transporting destination of materials is also proposed.
In the present invention materials are heated in a heat treatment chamber by operating a heating means such as a heater, but an on-line moisture control system which is more appropriate for saving energy by utilizing the retained heat of materials which have been heated in the heat chamber is also proposed.
In the preferred system of the present invention, the analyzed value obtained by a moisture measuring unit which executes titration and analysis by the use of titration reagent such as a Karl Fischer reagent and the weight of sampled materials before heat treatment or after heat treatment are sent to an operation unit to be calculated, whereby an accurate moisture content can be obtained quickly.
Also according to one possible system of the present invention, a dried inert gas is required to be introduced (or replaced) into a heat treatment chamber when powdered or granular materials are supplied into the chamber and the supplied materials are heated for moisture analysis. In this case a gas feeding means which can supply an inert gas through a control damper provided under the heat treatment chamber or a second control damper under a material storing chamber is provided.

DESCRIPTION OF EMBODIMENT

Other features and advantages of the invention will be apparent from the following description taken in connection with the accompanying drawings.

Fig. 1 is a schematic diagram showing a first system of the present invention;
Fig. 2 is a schematic diagram showing a second system of the present invention;
Fig. 3 is a schematic diagram showing a third system of the present invention;
Fig. 4 is a schematic diagram showing a fourth system of the present invention;
Fig. 4a is an enlarged sectional view of the main part of other preferable embodiment according to the present invention;
Figs. 5 and 6 are schematic diagrams of material storing chamber of other preferable embodiments according to the present invention;
Fig. 7 shows another preferable embodiment of control damper according to the present invention;
Fig. 8 illustrates the outer appearance of a coulometric moisture measuring unit; and
Fig. 9 is a block diagram showing the principle of the unit illustrated in Fig. 8.

Fig.1 shows a schematic diagram of a first system of the present invention.
In this system a heat treatment chamber 3 made of a heat-resistant glass provided with a heating means 4 at its periphery is disposed under a material sampling means 8A including a hopper 8 to store powdered or granular materials and a rotary valve 8a thereunder. The sampling means 8A and the heat chamber 3 are connected by a transport pipe P1 having a control valve 7a to control the material supply and a vent valve 7b to open to atmosphere, the valve 7a including a highly airtight valve disc to prevent the leakage of moisture produced when materials are heated in the chamber 3.
A material discharge port 3b provided under the chamber 3 is provided with a solenoid-operated control damper 5 which opens and closes the port 3b by reciprocating a valve disc 5a and a weight measuring unit 2 is provided under the damper 5.
The weight measuring unit 2 is equipped with a receiver 21 which can be opened and closed to receive the heated materials discharged from the port 3b of heat chamber 3. When the materials are received in the receiver 21, the weight is automatically measured and is converted into an electrical signal at a signal processor 2a of measuring unit 2, thus converted data being sent to an operation unit 10.
The heat treatment chamber 3 has a capacity enough to contain one sample of powdered or granular materials weighed by the rotary valve 8a and the upper part of the chamber 3 is connected with a branch pipe P2 having a control valve 1a and leading to a moisture measuring unit 1.
Many kinds of trace moisture measuring unit by means of a Karl Fischer reagent of which introduction port can be directly connected with the branch pipe P2 can be used as the moisture measuring unit 1. If such an unit is provided, a highly accurate coulometric or volumetric moisture measurement utilizing a Karl Fischer reagent can be achieved by supplying the moisture evaporated by heating materials into the unit 1 together with an inert gas and by inputting the weight of materials before heated.
The value titrated and analyzed by the moisture measuring unit 1 is converted into an electrical signal and sent to the operation unit 10, like the weight value measured by the weight measuring unit 2. Thus the titrated and analyzed value and the weight value are input into the operation unit 10, the moisture content being calculated, shown on a display 10a and printed out when required.
An inert gas feed port 6a is provided at the lower part of the heat chamber 3 and connected through a control valve 6b to a gas source 6 which feeds an inert gas such as a dried nitrogen gas or helium gas.
The heat treatment chamber 3 is equipped with a heating means 4 at its periphery constructed by Nesa electrodes or a well-known Nichrome wire. If the heating means 4 is constructed with Nesa electrodes, the materials in the heat chamber 3 can be seen through and also the body of chamber 3 can be made thin and compact.
The heat treatment chamber 3 is heated to and maintained the temperature just before the stored materials are vaporized in order to evaporate all the moisture contained in the materials. For this purpose, a temperature control unit 4a settles and controls the most appropriate temperature of the chamber 3 before containing materials depending on the materials to be heated therein.
According to this system, when sampling is required, the damper 5 is shut and the control valve 1a is closed to close the branch pipe P2 leading to the moisture measuring unit 1. At the same time the control vale 7a and the vent valve 7b are opened and the rotary valve 8a is driven to rotate while an inert gas is introduced into the chamber 3 by opening the control valve 6b, then samples are supplied into the chamber 3. At this time the vent valve 7b is opened to atmosphere to prevent an open air from entering into the chamber 3 when an inert gas is supplied into the chamber 3.
After a fixed amount of powdered or granular materials is thus contained in the chamber 3, the control valve 7a and the vent valve 7b are closed with the damper 5 still closed. And the control valve la is opened to open the branch pipe P2 leading to the moisture measuring unit 1 while the control valve 6b is opened to introduce an inert gas from the lower part of chamber 3 into all over the inside thereof.
Under these conditions, the materials are heated in the chamber 3 and the moisture produced by the evaporation of heated materials is supplied into the moisture measuring unit 1 together with the introduced inert gas.
The supply of inert gas continues until the measuring unit 1 detects the end of titration. When the unit 1 detects its end, the display 10a of operation unit 10 shows a sign indicating the end of titration.
After the heat treatment of powdered or granular materials is thus finished, the materials in the chamber 3 are supplied into the weight measuring unit 2 by opening the damper 5. In the unit 2 materials received at the receiver 21 are weighed and the value is converted into an electrical signal by the signal processor 2a then sent to the operation unit 10, wherein data sent from the moisture measuring unit 1 and the weight measuring unit 2 are calculated and the obtained moisture content of the materials is shown on the display 10a.
Fig.2 shows a schematic diagram of a second system of the present invention.
A weight measuring station 2A which is airtight and closed for open air is disposed under a material sampling means 8A constructed such that a rotary valve 8a to sample a fixed amount of powdered or granular materials is provided as a measuring device under a hopper 8 which stores the materials. The weight measuring station 2A is comprised of a weight measuring unit 2 having a receiver 21 to receive the materials and a supplementary hopper 22 to receive the materials weighed by the unit 2 and is provided with a vent valve 7b to open to atmosphere.
A heat treatment chamber 3 with an airtight heating means 4 having enough capacity to contain a fixed amount of materials weighed by the rotary valve 8a is disposed under the measuring station 2A. A branch pipe P2 having a control valve 1a and leading to a moisture measuring unit 1 is provided at the upper part of the heat chamber 3 and a feed port 6a of an inert gas feeding means 6A having a control valve 6b to control the introduction of a pressurized and dried inert gas into the chamber 3 is provided at the lower part of the chamber 3.
A control damper 5 to discharge materials is disposed under the chamber 3. The weight value of sampled materials measured by the weight measuring unit 2 and the value titrated and analyzed by the moisture measuring unit 1 are converted into electrical signals respectively and sent to an operation unit 10, as described in the first system.
According to this system, when sampling is required, the damper 5 is shut and the control valve 1a is closed to close the branch pipe P2 leading to the moisture measuring unit 1. At the same time a control vale 7a and the vent valve 7b are opened and the rotary valve 8a is driven to rotate while an inert gas is introduced into the chamber 3 by opening the control valve 6b, thus samples being supplied into the weight measuring station 2A. At this time the vent valve 7b is opened to atmosphere.
In the weight measuring station 2A a fixed amount of materials supplied by the rotary valve 8a is fallen into the receiver 21 of weight measuring unit 2 and received therein, then the weight is measured. Next, the materials are discharged into the supplementary hopper 22, fallen by gravity into the heat chamber 3 through a transport pipe P1 and heated therein.
In this system, the vent valve 7b to open to atmosphere equipped with the weight measuring station 2A is opened when an inert gas is fed into the station 2A through the heat chamber 3 at the same time materials are supplied into the station 2A, whereby the weight of materials is measured under closed and dried circumstances.
After a fixed amount of materials is thus supplied into the heat chamber 3, the control valve 7a and the vent valve 7b are closed with the control damper 5 still closed and an inert gas is introduced into the chamber 3 with the control valves 6b and 1a open, thus the moisture evaporated from heated materials being sent to the moisture measuring unit 1, as described in the first system.
The supply of inert gas continues until the measuring unit 1 detects the end of titration. When the unit 1 detects its end, a display 10a of operation unit 10 shows a sign indicating the end of titration. After the heat treatment of powdered or granular materials is thus finished, the materials are discharged by opening the control damper 5.
Like the first system of the present invention, the operation unit 10 calculates data sent from the moisture measuring unit 1 and the weight measuring unit 2 and shows the obtained moisture content of materials on its display 10a.
Fig.3 is a schematic diagram showing a third system of present invention.
In this system a rotary valve 8b provided in a material supply means 8A to transport powdered or granular materials doesn't work as a measuring device. A fixed amount of powdered or granular materials is weighed by a material measuring chamber 9 having a weight detection sensor S to detect the level of materials and provided between the material supply means 8A and a heat treatment chamber 3.
Materials are supplied into the material measuring chamber 9 by opening a control valve 7a until the sensor S detects that supplied materials reach a determined level. After a fixed amount of materials is stored in the chamber 9, the stored materials are supplied into the heat chamber 3 by opening a first control damper 51 provided between the measuring chamber 9 and the heat chamber 3.
A second control damper 52 to discharge the heated materials and a weight measuring unit 2 are provided under the heat treatment chamber 3, materials heated to be titrated and analyzed being weighed by the measuring unit 2.
An operation unit 10 calculates data sent from a moisture measuring unit 1 and the weight measuring unit 2 and indicates the obtained-moisture content of the materials on its display 10a. And other constructions are the same as the above-mentioned first system.
Fig.4 is a schematic diagram of a fourth system of present invention.
This system is characterized in that powdered or granular materials are supplied through a transport pipe line P4 by a pneumatic transportation by the use of a specially constructed material suction unit 81 which will be described hereinafter. The materials pneumatically transported by the unit 81 together with a pressurized gas are separated from the gas by a filtering device 14 provided at the entrance of material measuring chamber 9.
A capacitance level sensor S is provided with the chamber 9 as a weight detection sensor, controlling open and close operations of a control valve 7a to store a fixed amount of materials in the chamber 9.
The materials stored in the chamber 9 fall into a heat treatment chamber 3 by opening a first control damper 51 and are stored therein. At this time an inert gas introduced from a feed port 6a provided at the lower part of the heat chamber 3 is bled to atmosphere from the filtering device 14 passing through the heat chamber 3 and the measuring chamber 9. Therefore, both chambers 3 and 9 are prevented from entering of outer air and can be kept under dried circumstances which are suitable for measuring and analyzing moisture content.
The material suction unit 81 according to this system is constructed such that a pressurized gas injection port 82a of nozzle 82 is provided at the initial end side of material suction port 83 formed at the lateral leading portion of transport pipe 80 so as to be opposite to the transporting destination of materials. The suction port 83 of the unit 81 is inserted into a bed of powdered or granular materials M in a tank 85, materials being suck by injecting a pressurized gas from the nozzle 82 by operating a pressurized gas source 86.
Such a material suction unit 81 has been already disclosed in Japan by the present applicant. Materials are suck into the pipe 80 when a pressurized gas injected from the port 82a creates negative pressure at the suction port 83 by the effect of ejection, being transported under pressure by the pressurized gas injected from the nozzle 82. The nozzle 82 is free from clogging caused at the beginning of suction operation because the apparent area of suction port becomes larger than that of a conventional suction nozzle having the same caliber. Therefore, this system is preferable to execute an on-line pneumatic transportation of a small amount of materials by the use of a thin transport pipe.
Fig.4a is an enlarged sectional view of main part of other preferable embodiment according to the present invention.
In the figure, the system includes a heat treatment chamber 3 having a heating means 4 constructed by winding a Nichrome wire under a material measuring chamber 9 interposed by a first control damper 51, a material storing chamber 13, described hereinafter, provided under the heat chamber 3, a second control damper 52 under the chamber 13, and a weight measuring unit 2 having a receiver 21 to receive powdered or granular materials discharged from a material discharge port 13b of the storing chamber 13 under the damper 52.
Capacitance level sensors S and S1 are provided for the measuring chamber 9 and the storing chamber 13 respectively as a weight detection sensor. A transport pipe line P4 connected with the suction unit (see Fig.4) at its upstream end is connected with the upper end of measuring chamber 9 and a filtering unit 14 to separate the transported materials from a pressurized gas is provided at the side of the chamber 9.
The fist control damper 51 provided between the measuring chamber 9 and the heat chamber 3 includes a solenoid-operated highly airtight valve disc 51a. The solenoid-operated second control damper 52 disposed under the storing chamber 13 is constructed so as to be able to introduce an inert gas by filling a breathable ceramic material 53 in a gas introduction pipe 54 even if a valve disc 52a is closed, as described hereinafter. In the figure, the numeral 1a indicates a control valve interposed in a branch pipe P2 leading to a moisture measuring unit (shown as the numeral 1 in Fig.4) from the upper part of heat treatment chamber 3.
Fig. 5 shows another construction of material storing chamber according to the systems of present invention.
In Fig.5 a material storing chamber 13 to store at least more than one sample of materials is provided under a heat treatment chamber 3. A layer of powdered or granular materials to be heated is piled on a layer of materials stored in the storing chamber 13 and heated in the chamber 3.
After the materials of upper layer are heated in the chamber 3, the materials in the storing chamber 13 are discharged by gravitational fall when a valve disc 5a of control damper 5 is opened. A level sensor S1 is provided with the storing chamber 13 in order to control the amount of discharge, whereby immediately after one sample of materials is discharged, the valve disc 5a of damper 5 is closed, control valves 7a and 6b are opened and an inert gas is introduced into the chamber 13. At the same time a fixed amount of newly sampled materials is supplied into the heat treatment chamber 3 by a material supply means (not illustrated).
According to this system in which the material storing chamber 13 is provided under the heat treatment chamber 3, powdered or granular materials which have been already heated are stored in the storing chamber 13. Therefore, the chamber 3 is prevented from losing the heat by the supply of materials, contrary, the retained of materials heat can be applied to the above layer of materials, whereby an energysaving system and quick analysis can be achieved.
Further according to this system, an inert gas is introduced into the heat chamber 3 by opening the control valve 6b when a new sample of materials is supplied. So, this system is more effective to uniform the temperature in the heat chamber 3 because the inert gas works as a medium to transfer the heat of materials which have been already heated and the gas keeps the temperature in the chamber 3.
Furthermore according to this system, the weight of materials may be measured before heated by sampling a fixed amount of materials and feeding through the chamber 3 without executing heat treatment into a weight measuring unit 2. In this case, as the weight of measured materials at the measuring unit 2 differs from that of heated materials, the average weight of a few samples which are not heated may be used as the weight data in order to consider the difference between both weights.
Fig.6 shows a still another construction of material storing chamber according to the prevent invention preferably used in order to pneumatically transport sampled materials. This system also includes a material storing chamber 13 to store at least more than one sample of materials provided under a heat treatment chamber 3.
A layer of materials to be heated is piled on a layer of materials stored in the storing chamber 13 and heated in the heat chamber 3. After the heat treatment, the materials in the storing chamber 13 fall down by gravity and are discharged by opening a valve disc 52a of a second control damper 52. In order to control the discharging amount of materials, a level sensor S1 is provided with the storing chamber 13 as a weight detection sensor, whereby immediately after one sample of materials is discharged, the valve disc 52a is closed, control valves 7a and 6b are opened and an inert gas is introduced into the chamber 13. At this time a fixed amount of materials is supplied into the heat chamber 3 from the material measuring chamber 9 having a weight detection sensor S by opening a valve disc 51a of a first control damper 51. The effect of retained heat of materials in the storing chamber 13 is the same as the system shown in Fig.5.
Fig.7 shows a construction of another embodiment of a control damper provided under a heat treatment chamber 3.
A valve disc 5a of control damper 5 is provided with a valve port 5b to discharge materials and filled with a breathable ceramic material 53 so as to close a material discharge port 3b constructed under the heat chamber 3 when the valve disc 5a is at closed position. A gas introduction pipe 54 with one opened end is provided with the ceramic material 53 and the opening of the introduction pipe 54 is connected with a gas feed pipe P3' leading to a pressurized and dried inert gas source 6'.
According to such a construction, as the valve port 5b conforms to the discharge port 3b when the damper 5 is opened, powdered or granular materials m contained in the chamber 3 are discharged by gravitational fall through the port 3b as shown in Fig.7. When the damper 5 is closed, the ceramic material 53 closes the port 3b and prevent the discharge of materials m. However, an inert gas fed from the introduction pipe 54 successively goes into the heat chamber 3 because the gas can pass through the ceramic material 53, thus the replacement by inert gas, and the supply of an inert gas when materials are heated, as described heretofore, can be achieved.
Fig.7 shows only an embodiment of the damper 5 provided at the discharge port 3b of the heat treatment chamber 3, but in case that a material storing chamber 13 is further provided, a second control damper 52 provided at the material discharge port 13b of material storing chamber 13 may be similarly constructed.
In the above-mentioned embodiments sampled materials are weighed before heated or after heated by a weight measuring unit. However, such a weight measuring unit is removed and the apparent specific weight and the volume of sampled materials may be input into an operation unit. Such a system can further simplify the construction thereof because of the removal of weight measuring unit and is more effectively used for the moisture control of the same kind of powdered or granular materials.
In this case, the system may be preferably constructed such that the volume of sampled materials is input into the operation unit 10 automatically.

Claims

An on-line moisture control method for powdered or granular materials, by which the materials are repetitively sampled by the following steps:
feeding into a gastight heat treatment chamber (3) having a heating means (4) a fixed volumetric amount of the sampled materials delivered from a storage hopper via a measuring means (8);

heating the materials in said heat treatment chamber (3) while supplying the chamber with a pressurized and dried inert gas;

titrating and analyzing moisture generated by heating the materials in the chamber (3) by supplying the moisture, together with inert gas, to a moisture measuring unit (1);

discharging the heated materials from the chamber (3) into a receiver (21) of a weight measuring unit (2) provided under said heat treatment chamber (3) and measuring the weight of the discharged materials; and

automatically determining the moisture content of the sampled materials by supplying the moisture content value detected in said moisture measuring unit (1) and the weight measured in said weight measuring unit (2) to a calculating unit (10).
An on-line moisture control method for powdered or granular materials as set forth in claim 1, characterized by the modification that a fixed volumetric amount of the sampled materials from the hopper (8) is discharged into said heat treatment chamber via a weight measuring unit (2) in which air is replaced by inert gas supplied in the said weight measuring station (2A), whereby the sampled materials are weighed before the materials are supplied to a heat treatment chamber (3).
An on-line moisture control system for powdered or granular materials, said system comprising :
a materials sampling means (8A) provided with a hopper (8) having a valve (8a) for measuring a fixed volumetric amount of the powdered or granular materials;

a gastight heat treatment chamber (3) incorporating a heating means (4) and having a capacity sufficient to contain the fixed amount of sampled materials, said heat treatment chamber (3) being provided under said materials sampling means (8A):

a transport pipe (P1) provided between said sampling means (8A) and said heat treatment chamber (3), said transport pipe (P1) having a control valve (7a) to control supply of materials from said sampling means (8A) and having a gas vent valve (7b) for opening to atmosphere;

a moisture measuring unit (1) connecting to an upper part of said heat treatment chamber (3) via a branch pipe (P2) having a control valve (1a);

a control damper (5) provided under said heat treatment chamber (3) for discharging the materials from said heat treatment chamber (3);

an inert gas feeding means (6A) having a feed port (6a) at a lower part of said heat treatment chamber (3) and having a feed pipe (P3) incorporating a control valve (6b) for controlling introduction of pressurized and dried inert gas into said heat treatment chamber (3);

a weight measuring unit (2) provided under said control damper (5) for weighing the heated materials when discharged from the chamber (3); and

a calculating unit (10) which receives the weight value of sampled materials from said weight measuring unit (2) and the moisture content value of said materials from said moisture measuring unit (1), said calculating unit (10) calculating the moisture content of the fixed amount of the sampled materials and displaying the calculated moisture content value.
An on-line moisture control system for powdered or granular materials as set forth in claim 3, characterized by the modification that said weight measuring unit (2) is provided in a gastight measuring station (2A) provided with a vent valve (7b) and is provided over said heat treatment chamber (3) for weighing the sampled materials before the materials are heated in the heating chamber (3), said vent valve (7b) being opened, while a fixed volumetric amount of materials supplied from the hopper (8) is weighed to enable inert gas to be introduced from said inert gas supplying means (6A) via the heat treatment chamber (3) and replace air in said weight measuring unit (2).
An on-line moisture control system for powdered or granular materials as set forth in claim 4, characterized in that a material supply means to supply powdered or granular materials and a materials measuring chamber (9) having a level detection sensor (S) are provided in place of said material sampling and weighing means (8A), whereby the amount of sampled materials is measured by said sensor (S) in said materials measuring chamber (9).
An on-line moisture control system for powdered or granular materials as set forth in claim 3, characterized in that a materials suction unit (81) is provided instead of the materials sampling and weighing means (8A), said materials suction unit (81) having a nozzle (82) constructed so that a pressurized gas injection port (82a) is disposed on the upstream side of a materials suction port (83) formed at the leading portion of a transport pipe (80), and said nozzle (82) is inserted into a bed of powdered or granular materials (M) pneumatically to suck the materials downstream; and
a materials measuring chamber (9) is connected to said suction unit (81) by the transport pipe (80) and a transport pipeline (P4) having a control valve (7a), said materials measuring chamber (9) having a level detection sensor (S) and a filtering device (14) to separate the materials pneumatically transported by said suction unit (81) from the pressurized gas; and

a supplementary control damper (51) is provided between said materials measuring chamber (9) and said heat treatment chamber (3), the materials supplied by means of said materials suction unit(81) being weighed in said materials measuring chamber (9) while said supplementary control damper (51) is closed.
An on-line moisture control system for powdered or granular materials as set forth in any of claims 3, 4, 5 or 6, characterized in that a materials storage chamber (13) is provided under and open to said heat treatment chamber (3) and, instead of providing a control damper (5) beneath said heat treatment chamber (3) for discharging the fixed amount of materials from said heat treatment chamber (3), a control damper (5, 52) is provided beneath said materials storing chamber (13) for discharging the materials, whereby heat retained in said materials storing chamber (13) can be applied to the materials heated in said heat treatment chamber (3) while said control damper (5,52) is closed.
An on-line moisture control system for powdered or granular materials as set forth in claims 3, 4, 5, 6 or 7, characterised in that an opening for discharging the materials stored in said heat treatment chamber (3) and a gas introduction port (54) having a breathable material (53) is provided, together with said control damper (5, 52), in place of said inert gas feeding means (6A), said port (54) being connected with a feed pipe (P3') leading from an inert gas source (6') through a control valve (8b'), whereby pressurized and dried inert gas is supplied by connecting said gas introduction port (54) to a materials discharge port of said heat treatment chamber (3) when said damper (5, 52) is closed.
An on-line moisture control system for powdered or granular materials as set forth in claim 7, characterized in that a level sensor (S1) is provided for said materials storing chamber (13), a single sampled amount of heated materials being discharged from said materials storing chamber (13) by opening said control damper (5, 52) when said level sensor (S1) detects the said single sampling amount of material is stored.
An on-line moisture control system for powdered or granular materials as set forth in claims 3 or 4, 5, 6, 7, 8 or 9, characterized in that the volume and the weight of the sampled and weighed materials are input into said calculating unit (10) instead of providing said materials measuring unit (2).